RF-excited waveguide gas lasers are finding more applications as their reliability improves and their costs decrease. One of the keys to improving reliability is eliminating the presence of any particles which may intrude in the waveguide laser channels and smash into and damage the laser optics. One typical RF-excited waveguide laser assembly is described in Hart, U.S. Pat. No. 6,192,061. The RF-excited waveguide laser assembly of Hart consists of a pair of electrodes with dielectric waveguide insert sandwiched therebetween. Hart includes a pair of springs 26 which maintain the sandwich assembly in its desired configuration. One problem with a waveguide laser assembly as taught in Hart is the springs 26 as well as the sandwich assembly are slid into a housing interior and the lateral movement between the spring, the sandwiched assembly and the housing interior can generate particles which later can damage the optics in the manner described above.
Yet another problem with existing RF-excited waveguide gas lasers is that harmonic acoustic resonance during pulsed operation within the waveguide laser channels can adversely affect laser performance. Hart, U.S. Pat. No. 6,192,061 teaches providing a number of openings in the waveguide laser channel at positions about where a pressure peak of an acoustic resonance would be located. More particularly, Hart teaches providing such openings at about ¼, ½ and ¾ the lengths of each segment of a waveguide laser channel. These openings are provided substantially transverse to the optical axis of the waveguide laser channels. While such openings may be somewhat effective in diminishing harmonic acoustic resonance by venting gas from the waveguide channel, the openings provide only limited gas venting and fail to provide a suitable exit for particles that may intrude the waveguide laser channels, thus increasing the likelihood that any such particle will damage the waveguide optics.
Yet another known problem with existing RF-exited waveguide gas lasers is the waveguide laser channels are not configured to maximize higher order mode suppression while simultaneously maximizing uniform discharge formation.
The present invention is directed toward overcoming one or more of the problems discussed above.